What would you suggest for placing ads?
I just use google ads. Initially tried some BTC related ad services but quickly found google ads to make much more. One thing you cant do is ask people to click on your ads in support of the site. I hope miners realize that those ads help pay for hosting, etc. and if they see something that interested them they would click on it.

I really didn't spend much time optimizing the ads for the site. Kinda just threw them up there. I am fortunate that running the pools does not require an additional monthly cost. The equipment used (enterprise class physical servers) was probably in the $7k range (I forget...and that doesn't include all the auxiliary equipment) but had already been paid for and was not being utilized for anything else. Any expansion would have to be paid for out of pocket. I don't see it ever paying for itself.
The only motivation for me is that I consider this a hobby and find it fun to do. As a hobby any expense is just part of the cost to entertain myself.